went through this a month or so ago and ended up with the fox ranger 3l water”pants” and heartily recommend, especially on some of the deals round at the moment
fairly true to size as ended up with the 36 inch waste (what i take in most trousers), however take a 38 in other non waterproof fox trousers (defend etc). only down side is that knee pad room is a little constricted is using full on down hill pads – eg my Ion K-pacts where too big to be comfortable, but my fox launch D3O pads (which are lower profile) work fine.
first test of them was at a biblically wet day at BPW a few weeks ago and they were great. kept me warm and dry and knee pads were pretty much dry after a full day. used my fix defend trousers the next day (less wet) and was cold and wet by lunch
tried various others brands and they all had odd sizing, the royal storm pants being the worst offender – the XL wouldn’t even go over my hips and the XXL was unpleasantly tight on the waste and arse, but massive of the legs!